Mine were based on the (then) Harrison fibreglass frames and I had them trimmed quite thinly at the rear. With the cost of trimming, they were not cheap, but I was only going to do this once.
In this early photo (pre door re-trimming and professional carpeting) you can see that they can go back even further. I do have the extended body, however. The head restraints can be positioned quite high, but I suspect that they have to be fixed now?
